Individuals differ in the response of their LDL-C levels to dietary cholesterol and saturated fat. It has been suggested that variation in cholesterol absorption may explain some of these differences. We intend to study individuals on low fat - low cholesterol, high fat - high cholesterol, and high fat - low cholesterol diets. This will allow us to determine under highly controlled metabolic ward conditions whether cholesterol absorption is a determinant of LDL-C levels and diet response.